does whatIf validate vm size and ip addresses

Just started using WhatIf to validate my templates and I thought this would be covered but perhaps it doesn't.

When I pass in bogus IP address and vm sizes (via -TemplateParameterObject) it still succeeds.
Is Get-AzResourceGroupDeploymentWhatIfResult supposed to validate these things?

```
$templateParams = @{}
$templateParams.Add("virtualMachineSize","Standard_E8s_v3_no_such_size")
$templateParams.Add("staticIpAddress","10.20.30.400")

$results = (Get-AzResourceGroupDeploymentWhatIfResult `
-ResourceGroupName "$AzureResourceGroupName" `
-TemplateFile "$ArmTemplatePath" `
-TemplateParameterObject $templateParams)
```

The results contain:

```
+ Microsoft.Compute/virtualMachines/vm-usw-oo-test2-db-99 [2020-06-01]

apiVersion: "2020-06-01"
id: "/subscriptions/my-subscription/.../Microsoft.Compute/virtualMachines/my-vm"
location: "westus"
name: "my-vm"
properties.diagnosticsProfile.bootDiagnostics.enabled: true
properties.diagnosticsProfile.bootDiagnostics.storageUri: "https://sta1my1vm1.blob.core.windows.net/"
properties.hardwareProfile.vmSize: "Standard_E8s_v3_no_such_size"
```

and

```
+ Microsoft.Network/networkInterfaces/nic-usw-oo-test2-db99 [2020-07-01]

apiVersion: "2020-07-01"
id: "/subscriptions/my-subscription/.../Microsoft.Compute/virtualMachines/my-vm"
location: "westus"
name: "nic-my-vm"
properties.ipConfigurations: [
0:
name: "ipconfig1"
properties.privateIPAddress: "10.20.30.400"
properties.privateIPAllocationMethod: "Static"
```

Start by reproducing the shown Get-AzResourceGroupDeploymentWhatIfResult call with the bogus virtualMachineSize and staticIpAddress values. Compare the What-If output with deployment validation and determine whether either value is expected to be rejected; the issue names no repository files or tests, so done means documenting the validation boundary or identifying an actionable repository change.

Written by the indexing model from the issue text.